Language switch implemented

utils/reducer.ts

@@ -1,7 +1,4 @@
-export enum Actions {
-    "SET_FIELD",
-    "SET_ALL"
-}
+import { replaceBoth } from "./language";
 
 export const initialState = {
     source: "auto",
@@ -9,6 +6,14 @@ export const initialState = {
     query: ""
 }
 
+type State = typeof initialState;
+
+export enum Actions {
+    SET_FIELD,
+    SET_ALL,
+    SWITCH_LANGS
+}
+
 type Action = {
     type: Actions.SET_FIELD,
     payload: {
@@ -18,19 +23,31 @@ type Action = {
 } | {
     type: Actions.SET_ALL,
     payload: {
-        state: {
-            [key: string]: string
-        }
+        state: State
     }
+} | {
+    type: Actions.SWITCH_LANGS
 }
 
-export default function reducer(state: typeof initialState, action: Action) {
+export default function reducer(state: State, action: Action) {
     switch (action.type) {
         case Actions.SET_FIELD:
             const { key, value } = action.payload;
             return { ...state, [key]: value };
         case Actions.SET_ALL:
             return { ...state, ...action.payload.state };
+        case Actions.SWITCH_LANGS:
+            const { source, target } = replaceBoth("exception", {
+                source: state.target,
+                target: state.source
+            });
+            return {
+                ...state,
+                source: source !== target
+                    ? source
+                    : initialState.source,
+                target
+            };
         default:
             return state;
     }